Elements
and
Compounds
NPS/NAFL NORTH
5
ELEMENTS
AND
COMPOUNDS
NPSNAFLNORTH|
KOCL|May2021
Contents
Atoms and Molecules Page 3
Elements and Compounds Page 8
Molecules Page 9
Compounds Page 10
Mixtures Page 11
The Changes of States of Matter Page 15
Introduction to the Periodic Table Page 23
Activity Page 25
Vocabulary Page 27
Matter
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ATOMS AND MOLECULES
Some examples of
matter are wood, water
and air.
Matter is found in 3
states:
•Solid
•Liquid
•Gas
Everything that we can touch, see
and feel is made up of matter.
Even air is made up of matter.
Matter is anything that has mass
and occupies space.
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ATOMS AND MOLECULES
Matter is made up of extremely small particles called
molecules.
Different substances are made up of different kinds molecules.
Every molecule of a substance shows the properties of that
substance. Hence, the molecules of one substance are different
from the molecules of another substance.
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MATTER
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Atoms
Atoms are the "building blocks" that make up EVERYTHING!
Atoms are very, very small. They are so small that they can only be
seen under a special microscope called an electron microscope.
They are so small that millions of them could fit on the head of a pin.
There are different kinds of atoms.
Molecules
When two or more atoms combine and
join, they create a molecule.
Molecules can be made from the same
kind of atoms or combinations of
different atoms. All molecules are made
from atoms, but they look different
because of the way they are put together.
MATTER
Look at the pictures below: They are made of atoms but are put
together differently.
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Oxygen Carbon Hydrogen
CO2
Carbon-dioxide Molecule
H2O
Water Molecule
H2
Hydrogen Molecule
OCH
O
O
O2
Oxygen
Molecule
O
O
C
O
H
H
H
H
Atom Molecules
-Combinations of
different atoms
SOME MOLECULES HAVE A SMALL 2 AFTER A LETTER WHICH MEANS IT HAS TWO ATOMS IN IT.
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MATTER
ELEMENTS AND COMPOUNDS
What is an element?
A substance that is made up of a single type of
atom is called an element. Oxygen, chlorine, gold,
hydrogen and carbon are examples of elements.
Some elements like iron, gold, silver and copper
are metals while some like carbon, oxygen and
nitrogen are not metals.
Atoms found in one element are not found in any
other element.
Every kind of atom has its own unique
properties. That is why every element is different
from all other elements. For example, the element
gold is different from every other element.
Fe
Symbol
for Iron
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ELEMENTS AND COMPOUNDS
COMPOUNDS
The molecules of some substances are made up of more than one type
of atom. Such substances are called compounds.
Water is a compound. The water molecule is made up of two different
types of elements - Hydrogen and Oxygen.
Do you know why a
compound is different from
the elements, that make it?
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COMPOUNDS
Two Hydrogen atoms and one Oxygen
atom join together to form a molecule of
water. The molecule of a compound is
its smallest part. It has all the properties
of a compound.
A molecule of water has all the
properties of water. Carbon dioxide,
table salt and sugar are examples of
some other compounds.
O
A compound is made up of atoms of more than one type of
elements. You know that water is a liquid. It is made up of two
different types of elements—Hydrogen and Oxygen.
Hydrogen and Oxygen are gases at room temperature. Hydrogen is
a gas that burns easily, whereas Oxygen supports the process of
burning.
Water is not like either of the elements it is made up of. This is
true in the case of all compounds. A compound is always different
from the elements that make it.
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CO2
Carbon-dioxide Molecule
H2O
Water Molecule
O
CO
H
H
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COMPOUND
MIXTURES
A mixture is a substance made up of two or more elements
or compounds when physically mixed in any ratio.
Ice-cream, sugar syrup, salt solution, smoke, ink and paints
are a few examples of mixtures.
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Mixture of grains Mixture of gems, groundnuts and seeds
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MIXTURES
Salt Water Mixture
mixture of
salt and
water
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The constituents in a mixture may be present in any ratio or proportion.
For example, in a mixture of salt and water, the amount of salt and water
is not fixed. A mixture of salt and water can be prepared with one, two
or more spoons of salt. Irrespective of the number of spoons of salt, the
combination of water and salt is still a mixture.
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CHARACTERISTICS OFMIXTURES
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CHARACTERISTICS OFMIXTURES
A mixture does not have any specific property of its own. In a
mixture, each constituent exhibits its original properties.
For example, pure oxygen supports burning and so does the
oxygen present in air. Similarly, the taste of salt is salty on its
own, and it also tastes salty when mixed with water.
A mixture does not have a fixed melting or boiling point.
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Heating and cooling can change the arrangement of molecules in a
substance and thereby its state.
On heating, molecules move further apart and a solid changes to a
liquid and a liquid into a gas.
Just the opposite happens when a substance is cooled. The
molecules move closer and so a gas changes into a liquid and a
liquid into a solid.
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CHANGES OFSTATES OFMATTER
Condenses
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A solution is formed when a substance dissolves in a liquid.
The substance which dissolves in the liquid is known as a solute.
The liquid in which the solute dissolves is called the solvent. When
salt is added to water, a salt solution is formed. Salt is the solute
and water is the solvent
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SOLUTION AND SOLVENT
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When two liquids mix together,
they are called miscible liquids.
Eg. Honey and water are miscible
liquids.
Some liquids do not dissolve in
water. For example, cooking oil
and water do not mix.
Such liquids are called immiscible
liquids.
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LIQUIDS INWATER
Immiscible Liquids
The world around us changes continuously. Changes are of two
types- physical and chemical.
Physical change: A physical change is a temporary change. It does
not result in the formation of a new substance as the properties
of the substance do not change.
For example, the formation of a salt solution is a physical change
because both salt and water can be easily separated.
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CHANGES AROUND US
A chemical change forms one or more new substances. A
chemical change is mostly irreversible and permanent.
For example, if sugar is heated continuously, it changes into a new
black substance. The new substance formed is carbon. It does not
have the properties of sugar. Similarly burning of paper brings
about a chemical change. The paper is reduced to ash. Ash cannot
be converted into paper again.
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dosa batter changed into dosa
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CHEMICAL CHANGE
INTRODUCTION TO THE PERIODIC TABLE
Some elements like iron, gold, silver and copper are metals while some
like carbon, oxygen and nitrogen are not metals.
Atoms found in one element are not found in any other element.
Every element has a specific name given by the International Union of
Pure and Applied Chemistry (IUPAC).
Since there are numerous elements, it is easy to refer to them using
symbols rather than their full names all the time.
Most elements are obtained from nature, there are 92 naturally
occurring elements.
Only a few can be made in the laboratory by scientists and these man-
made elements can only be made in very small quantities.
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1
2
3
4
5
6
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INTRODUCTION TOTHE PERIODIC TABLE
Elements Symbols
Al
uminium Al
Br
omos (Greek) - Bromine Br
C
hlorine Cl
Co
balt Co
Cu
prum (Latin) - Copper Cu
Fe
rrum (Latin) - Iron Fe
He
lium He
H
ydrogen H
Iodine
I
K
alium (Latin) - Potassium K
M
agnesium Mg
Na
trium (Latin) - Sodium Na
S
ulphur S
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SOME COMMON ELEMENTS AND THEIR SYMBOLS
ACTIVITY
Make models of molecules with
toothpicks and coloured balls of clay.
Start with a water molecule. Choose a
colour to be oxygen and a colour to be
hydrogen. Attach the two hydrogen
balls to the oxygen ball with the
toothpicks so it looks like this diagram:
After you have finished making the water molecule, make
these molecules:
1
2
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ACTIVITY
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From the activity we can see that “di” means two, so carbon
dioxide means a carbon molecule with two oxygen molecules.
“Tetra” means four, so carbon tetrachloride means a carbon
molecule with four chlorine molecules.
Info Zone
Oxygen is an element. It usually occurs as oxygen gas and ozone
gas. Being an element, it is made up of only one type of atom. But
the molecules of oxygen and ozone are different. The oxygen
molecule is made up of two atoms of oxygen whereas the ozone
molecule has three atoms of oxygen.
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ACTIVITY
compound-a substance whose molecules are made up of
more than one type of atom
element-a substance that is made up of a single type of atom
mixture-a substance that is made up of two or more elements
or compounds when physically mixed in any ratio
molecule-the smallest part of an element that has all its
properties
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VOCABULARY
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VOCABULARY
